U.S. Pat. No. 4,452,948 describes a coating composition suitable for use as a glossy pigmented coating for a rigid substrate, particularly where hardening of the coating at ambient temperatures is required, for example as a vehicle refinishing paint. The coating composition comprises a hydroxy component having at least two free hydroxy groups per molecule and an anhydride component having at least two cyclic carboxylic acid anhydride groups per molecule, at least one of these components being a film-forming polymer. The composition also includes a catalytically effective amount of amine groups, preferably present on the hydroxy component, for accelerating the curing reaction between the hydroxl groups and the anhydride groups.
European Patent Application 259172 describes a coating composition comprising an anhydride polymer containing at least two cyclic carboxylic acid anhydride groups and a polymer containing at least two functional groups reactive with anhydride groups. These reactive groups are selected from hydroxyalkylamino, hydroxyalkoxyalkylamino, hydroxy-substituted acyloxyalkylamino, hydroxy-substituted polyacyloxyalkylamino, mercaptoalkylamino and oxazolidino groups. One of the polymers comprises a flexible polymer chain selected from polyether, polyester, silicone, diene polymer, hydrogenated diene polymer, polyurethane, polyisobutylene and polyacrylate chains. The functional groups characteristic of that polymer are each present as a terminal group at the end of a flexible polymer chain. The cured coatings have increased resistance to impact and abrasion.
U.S. Pat. No. 4,798,745 describes a coating composition comprising a hydroxy component having at least two free hydroxy groups per molecule and an anhydride component having at least two carboxylic anhydride groups per molecule used in amounts to provide a ratio of equivalents of hydroxy groups to equivalents of anhydride groups of 3:1 to 1:3. The anhydride component is a copolymer of at least 11% by weight of an ethylenically unsaturated anhydride with a vinyl comonomer such as styrene which is used in a molar proportion of at least 1:1 with respect to the unsaturated anhydride.
Liu et al in J. Polymer Science, Part A: Polymer Chemistry, 26, pages 3015 to 3029 (1988), describe the preparation of 1,1'-bis(2-hydroxyethyl)-2,2'-biimidazole and its use in synthesising a series of new polyurethanes based on aromatic diisocyanates. Derwent Patent Abstract 83-829562 (an abstract of Japanese Patent Application 58-179271) describes a coating composition comprising a reaction product of a bis(hydroxy-imidazoline) and an epoxy resin, the product being neutralised with a volatile acid.